[PATCH v1 0/1] Mediatek uart patch

[zhiyong.tao]

On Thu, 2021-07-29 at 08:03 +0200, Greg KH wrote:
> On Thu, Jul 29, 2021 at 09:48:16AM +0800, Zhiyong Tao wrote:
> > This series includes 1 patches:
> > 1.fix uart corruption issue when rx power off
> > 
> > when uart is used as a communication port with external
> > device(GPS).
> > when external device(GPS) power off, the power of rx pin is also
> > from
> > 1.8v to 0v. Even if there is not any data in rx. But uart rx pin
> > can
> > capture the data "0".
> > If uart don't receive any data in specified cycle, uart will
> > generates
> > BI(Break interrupt) interrupt.
> > If external device(GPS) power off, we found that BI interrupt
> > appeared
> > continuously and very frequently.
> > When uart interrupt type is BI, uart IRQ handler(8250 framwork
> > API:serial8250_handle_irq) will push data to tty buffer.
> > The code path:
> > 
https://elixir.bootlin.com/linux/latest/source/drivers/tty/serial/8250/8250_port.c#L1917
> > mtk8250_dma_rx_complete is a task of mtk_uart_apdma_rx_handler.
> > mtk8250_dma_rx_complete priority is lower than uart irq
> > handler(serial8250_handle_irq).
> > if we are in process of mtk8250_dma_rx_complete, uart appear BI
> > interrupt:1)serial8250_handle_irq will priority execution.2)it may
> > cause
> > write tty buffer conflict in mtk8250_dma_rx_complete.
> > So the spin lock protect the rx receive data process is not break.
> 
> All of this information should be in the changelog for the patch
> itself.
> There is no need for a "cover letter" for a single patch like this.
> 
> Can you redo your 1/1 patch and add the above information to the
> changelog text and resend it as a v2?
> 
> thanks,
> 
> greg k-h

Dear greg,

Thanks for your suggestion. we will move it to patch 1/1 in v2.

Thanks.